One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,7,8,5)(9,10)(11,15)(12,14)(13,16)(17,19)(18,23)(20,22)(21,24)(26,31)(27,28)(33,38)(35,36)(1,3,4,8)(2,5,6,7)(9,10)(11,17)(12,14)(13,16)(15,19)(18,24)(20,22)(21,23)(25,26,30,31)(27,32,28,34)(29,33,37,38)(35,39,36,40)(1,3)(2,5)(4,8)(6,7)(10,12)(15,17)(16,20)(23,24)(25,27,30,28)(26,32,31,34)(29,35,37,36)(33,39,38,40)(1,3)(2,5)(4,8)(6,7)(9,11)(10,15)(12,17)(13,21)(14,19)(16,24)(18,22)(20,23)(25,28,30,27)(26,32,31,34)(29,35,37,36)(33,40,38,39)(1,2)(3,5)(4,6)(7,8)(9,12,14,10)(11,17,19,15)(13,20,22,16)(18,24,21,23)(25,26)(27,34)(28,32)(29,33)(30,31)(35,40)(36,39)(37,38)(9,13,14,22)(10,16,12,20)(11,18,19,21)(15,23,17,24)(25,29,30,37)(26,33,31,38)(27,35,28,36)(32,39,34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.